Processes for forming metal films by atomic layer deposition
Publication Date: 2004-May-03
The IP.com Prior Art Database
BY ATOMIC LAYER DEPOSITION
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to processes for forming metal films on a substrate by atomic layer deposition. More specifically, the present invention is related to forming metal films by atomic layer deposition using metal-containing compounds and carbon monoxide (CO). The processes of the present invention have particular applicability in the semiconductor manufacturing industry.
2. Description of the Related Art
In the semiconductor manufacturing industry, metal films are deposited on the surface of a semiconductor substrate for purposes of wiring and device interconnection. Examples of metals used for device interconnection include, but are not limited to, aluminum, copper, tungsten and their alloys. In recent years, copper-based films have become preferred over aluminum-based films due to their lower resistivity and better resistance to electromigration.
Atomic layer deposition (ALD) processes, for example, are promising techniques for deposition of metallic films. ALD processes are desirable because they allow very precise composition control and conformal coverage of high-aspect-ratio features over the substrate surface.
ALD processes often employ volatile precursors such as, for example, organometallic precursors, that are decomposed to form a desired film on a substrate in a process chamber.
In ALD, a first compound is introduced to a vacuum process chamber in a first reaction step during which the first compound is deposited on the substrate surface. An inert gas, for example, nitrogen, is introduced into the process chamber and excess of the first compound is purged from the process chamber. A second compound is then introduced into the process chamber where it reacts with the first compound adsorbed on the substrate surface to complete formation of the desired layer. An inert purge gas is then introduced into the chamber to remove the second compound from the process chamber. This sequence of steps may be repeated to generate additional layers, until a desired overall layer thickness is achieved.
In the case of metal film deposition, there are numerous precursors that are suitable for thin-film deposition including, but not limited to, precursors such as Cu(I) and Cu(II) precursors such as CuCl; copper diketonates, for example, Cu(II)-2,2,6,6-tetramethyl-3,5-heptanedionate (Cu(thd)2); Cu(II) hexafluoroacetylacetonate (Cu(hfac)2); Cu(II) acetylacetonate (Cu(acac)2 ); copper ketoesters, for example, those described in U.S. Patent No. 5,441,766 to Choi et al., the disclosure of which is hereby incorporated by reference in its entirety; copper compounds containing Si...